Axial fan construction



Jan. 25, 1966 J. w. SCHROETER ETAL 3,231,022

AXIAL FAN CONSTRUCTION Filed March 9, 1964 INVENTOR foczcZzz'm Z11 50510621 192 W6 Fi AT TORNE 1 United States Patent 3,231,022 AXIAL FAN CONSTRUCTION Joachim W. Schroeter, Depew, and Derrei N. Stewart, Hamburg, N.Y., assignors to Buffalo Forge Company, Buffalo, N .Y., a corporation of New York Filed Mar. 9, 1964, Ser. No. 350,376 2 Claims. (Cl. 17016t).6)

The present invention relates to an axial fan and more particularly to an improved construction for adjustably mounting individual fan blades on an associated hub.

in the past various constructions have been utilized for mounting fan blades on the hub of an axial fan. However these constructions have had certain shortcomings. More specifically, certain of these constructions required access to the inside of the hub for the purpose of adjusting the pitch of the blades. With such constructions it was extremely difficult to vary the pitch of the blades because the securing structure on the inside of the hub was not easily accessible. Furthermore While other prior constructions permitted the adjustment of the pitch of the blades from the outside of the hub, such constructions were either relatively complex or were inherently incapable of providing a permanent tight connection between the blade and the hub which resulted in the loosening of the blades with the attendant changing of their pitch during fan operation. It is with the overcoming of the foregoing shortcomings of prior axial fan constructions that the present invention is concerned.

It is accordingly an important object of the present invention to provide an improved axial fan construction which permits replaceable blades to be both selectively adjusted from a position external to the hub and which also includes an improved structure for securely locking said blades in their adjusted position against changing of pitch during operation.

Another object of the present invention is to provide an improved axial fan construction having selectively replaceable and adjustable blades which utilizes an extremely simple attaching structure forsecuring the blades to the hub. Other objects and attendant advantages of the present invention will readily be perceived hereafter.

The improved axial fan construction of the present invention include a hub having radially spaced internal and external planar Wall portions associated with each blade. Each blade'in turn has an airfoil portion and located proximate the base thereof is a collar having a planar surface which is adapted to engage the external planar surface of the hub. A plate member, which is separate from the remainder of the blade portion, has a planar surface which is adapted to engage the internal planar surface of the hub. Tie members, such as screws, are located on opposite sides of the airfoil portion and extend through aligned apertures in said collar and said plate member. By tightening these tie members, the plate member and collar are drawn toward each other, and the planar surfaces thereon engage associated planar surfaces of said hub to thereby securely clamp a portion of said hub therebetween. The foregoing construction in addition to being extremely simple and inexpensive, provides an extremely tight connection because of the relatively large bearing areas between the hub and the collar and between the plate and the hub. It can readily be appreciated that the above-mentioned planar surfaces, in addition to providing the above-described tight connection, also cause the entire structure to be economical from a fabrication aspect. Furthermore the above-mentioned threaded members can be manipulated from a position external to the hub to permit the pitch of the blade to be adjusted without a requirement for access to the internal portion of the hub. The various aspects of the present invention will more readily be perceived hereafter when the following portions of the specification are read in conjunction with the accompanying drawings wherein:

FIG. 1 is a fragmentary rear elevational view of the improved fan construction of the present invention;

FIG. 2 is a view taken substantially along line 22 of FIG. 1;

FIG. 3 is a view taken substantially along line 3-3 of FIG. 2;

FIG. 4 is a view taken substantially along line 4'4 of FIG. 2;

FIG. 5 is a view taken substantially along line 55 of FIG. 3; and

FIG. 6 is a fragmentary elevational view of a modified form of hub construction which is manifestly suitable for use with the fastening arrangement of the present invention.

In FIGS. 1 and 2 a hub 10 is shown having a circumferential peripheral wall portion 11 secured to a Web 12 which is in turn mounted on a tapered sleeve 13 by means of screws 14, said tapered sleeve being attached to shaft 15 which is driven by a suitable motor, not shown.

The peripheral wall 11 of hub 10 has a plurality of circumferentially spaced apertures 16 therein. An internal planar surface 17 is located on an internal portion of wall 11 surrounding each of said apertures 16 and a planar surface 18 located on the external portion of said hub surrounding each of said apertures 16. At this point it will be noted that the fastening construction will be described only with respect to a single blade 19 and that the fastening construction for other blades to be associated with other of said apertures 16 are identical.

Blade 19 includes an airfoil portion 20 having an outer tip 21 and a base portion 22. It will be appreciated that the fan construction which includes a hub and a plurality of blades is adapted to rotate within cylindrical duct 23. Located proximate the base portion 22 of airfoil portion 2@ is a collar 24 which is, in this instance, formed integrally therewith and which is of generally cylindrical configuration so that it can fit snugly within counterbore 25 in hub portion 11. The lower surface 26 of collar 24 is planar to provide good bearing contact with planar surface 13 of'hub portion 11. It is to-be noted at this point that there is 360 contact between collar surface 26 and planar surface 18, and this amount of contact stabilizes the blade in its mounted position.

A separate plate member 2'7 which is shown as being of solid rectangular configuration, but which may be of any other suitable configuration, is spacedly positioned relative to collar 24 so that a clearance exists therebetween. Plate 27 includes an upper planar surface 28, a portion of which is adapted to engage planar surface 17 of hub portion 11 in firm bearing contact. It .is-to be noted that the simplicity of fabrication of the planar surfaces 18, 2d, 28, and 17 contributes greatly to the economy of the instant construction.

To complete the assembly, screws 29, which are essentially tie members, extend between aligned apertures 30 and 31 (FIG. 5) in collar 24 and plate 27. At this point it is to be noted that the ends 32 of screwsl29 are threaded and are received in apertures 31 which are tapped. Devices are provided for preventing undesired turning of screws 29 after they are tightened, and in this instance a device 35 which is commercially known by the trademark Hell-Coil is used, this device being ahelical coil of metallic material which fits between the threads at the ends of screws 32 and the tapped holes 31. Mild steel can be used for plates 2'7 because the Heli-Coil construction strengthens the tapped holes against stripping. The Heli-Coil is of the type which serves the dual function of both strengthening the .threads and locking the screws against undesired loosening. A Heli-Coil of this type is shown in Bulletin 800, page 1, dated 1962, of

the Heli-Coil Corporation, of Danbury, Connecticut. As can readily be seen from FIG. 5, screws 29 extend through circular aperture 16 in hub portion 11 to provide for unrestricted movement of said screws about the longitudinal axis of blade 19 incidental to the adjustment of pitch of the latter.

It will be noted that the heads of screws 29 are located within counterbores 33 in collar 24 and that said screw heads can be engaged by a hexagonal wrench andtherefore be manipulated from a position external to hub for the purpose of tightening and loosening blade 19. More specifically, assuming that blade 19 is in a first position, in order togchange its pitch it is merely necessary to loosen screws 29 from a location externally of hub 10, manually adjust blade 19 while using the index marks of FIG. 3 as a reference, and thereafter retighten screws 29 to sandwich a portion of hub 11 surrounding the walls of aperture 16 between the planar surfaces 28 and 26 of plate 27 and collar 24, respectively. Because there can be unlimited relative rotation between the blade and the hub on which it is mounted, it will be appreciated that the direction of air flow can be reversed without changing the direction of rotation of the fan by suitably adjusting the pitch of the blades.

In FIG. 6 a modified form of hub 10' is shown. This hub does not have the polygonal internal peripheral surface of FIG. 1 but has a substantially circular internal peripheral surface 40. Peripherally spaced on surface 44 are counterbores 41 for receiving plate 27 associated with each blade. It will be appreciated that by making the internal peripheral surface of hub 10' circular rather than polygonal a single hub can be utilized for mounting different numbers of blades by merely varying the circumferential distance between counterbores 41. In contrast to this, a hub such as 10 of FIG. 1 is limited to a given number of blades. More specifically, assuming that for a given application it is found that nine blades are an optimum number, the counterbores 40 will be spaced apart a distance of one-ninth of 360 and such spacing is effected on a standard hub 10', which under other circumstances can have the counterbores spaced different amounts, as required.

It is to be especailly noted that because all of the interengaging surfaces for securing the blade to the hub are planar and of relatively large area, the pitch of the blade can be adjusted and readjusted Without mutilation of the joined elements, thereby insuring their longevity. Also, 360 contact between collar surface 26 and hub surface 18 provides for an extremely stable mounting of the blade. It will also be noted that the distribution of forces resulting from the foregoing construction permits the utilization of a thinner hub section than would otherwise be required with other fastening constructions. In addition, because planar parts are utilized to effect the abovedescribed mounting of the blade on its associated hub, the fabrication of such parts and of the hub is relatively simple and inexpensive. Furthermore by locating the screws 29 on opposite sides of the airfoil, a balanced construction is obtained utilizing a plurality of screw members to further enhance the firm engagement between the associated parts. In short, the instant mounting construction provides an extremely simple and reliable arrangement for firmly mounting an axial fan blade on an associated hub while permitting pitch adjustment from the. outside of said hub.

While a preferred embodiment of the present invention has been disclosed, it will readily be appreciated that it is not limited thereto, but may be otherwise embodied.

We claim:

1. A blade construction adapted to be mounted in firm clamped engagement on a portion of a hub having an internal peripheral wall portion and an external peripheral wall portion comprising a blade portion having a base, a hub having an internal and an external peripheral wall portion, said blade portion including a collar located proximate the base thereof, said collar having a first SLl1'-' face adapted to engage said external peripheral wall por-- tion of said hub, a plate member having a second surface adapted to engage said internal peripheral Wall portion of said hub, said blade portion and said plate having aclearance therebetween in their mounted position, aperture means in said hub, tie means on opposite sides of said blade portion extending through said aperture means and between said collar and said plate member for drawing said collar and said plate member toward each other until said collar and said plate member mount said blade construction against movement on said hub by sandwiching a portion of said hub in firm clamped engagement between said first and second surfaces, means forming a part of said tie means and located proximate said peripheral external surface for effecting loosening and tightening of said tie means from a position external to said hub, said loosening of said tie means permitting adjustment of said blade construction on said hub by increasing the clearance between said plate member and said collar and thereby permitting movement of said blade construction on said hub, and means associated with said tie means for locking said tie means against; undesired loosening after said tie a means have beentightened.

2. An axial fan for mounting a plurality of individually adjustable blades in rigid clamping engagement errata associated hub comprising a hub having a wall with aplurality of opposed outer and inner planar portions cit cumferentially located along the periphery of said hub, circumferentially spaced apertures in said wall extend-- ing from each of said outer planar portions to each of said inner planar portions; a plurality of blades, each of said blades having an airfoil portion and a collar located proximate the base of said airfoil portion, a first and second aperture in each of said collars on opposite sides of said airfoil portions, each of said collars having a planar surface adapted to engage an associated outer planar wall portion, a plate member spacedly located from each of said collars, 'a clearance between associated plate members and said blades, each of said plate members having third and fourth apertures therein, said third apertures being in alignment with said first apertures and said fourth apertures being in alignment with said second apertures, each of said plate members having a planar surface for engaging an associated internal planar portion of said hub, first threaded means extending through each of said' first and third apertures and second threaded means ex-- tending through each of said second and fourth apertures for drawing each of said plate members and said collars toward each other to thereby effect said rigid clamping; engagement on said associated hub in view of said clearance between said plate members and said blades, and means for permitting the manipulation of each of said first and second threaded means from a position proximate said external portions of said hub to thereby effect the loosening and tightening of said threaded means for varying the clearance betweeneach of said blades and each of said plate members to thereby permit the loosening of each of said blades by increasing of said clearance for purposes of adjustment from a position external to the hub and for permitting the tightening of each of said blades by causing said plate members to approach said collars by decreasing of said clearance in response to the tightening of said first and second threaded means to thereby cause said planar surface of each of said collars tofirmly engage associated external planar surfaces of said hub and to cause each of said planar surfaces of said plate.- members to firmly engagev associated internal planar surfaces of said hub to thereby sandwich portions of said hubin rigid clamping engagement between said collars and. said plate members to thereby securely fasten said blades: against movement on said hub after said first and second. threaded means have been tightened, and means associated with said threaded means for locking said threaded means 5 6 against undesired loosening after said threaded means 2,981,338 4/1961 Hindmarch 170160.6 have been tightened. 3,013,615 12/1961 Pehrsson 170160.58

FOREIGN PATENTS References Cited by the Examiner 1,241,555 8/1960 France.

5 945 237 ZTAEES PATENTS 170 173 367,265 2/1932 Great Britain.

J 0W en 1,878,816 9/1932 Bucklen 170160.6 562711 7/1944 Great Bntam' 2,101,535 12/1937 Engdahl 170160.6 SAMUEL LEVINE Primary Examiner. 2,501,908 3/1950 Nichols 170--160.22

2,812,028 11/1957 Halvorsen 170-160.58 JULIUS WEST, Examiner- 

1. A BLADE CONSTRUCTION ADAPTED TO BE MOUNTED IN FIRM CLAMPED ENGAGEMENT ON A PORTION OF A HUB HAVING AN INTERNAL PERIPHERAL WALL PORTION AND AN EXTERNAL PERIPHERAL WALL PORTION COMPRISING A BLADE PORTION HAVING A BASE, A HUB HAVING AN INTERNAL AND AN EXTERNAL PERIPHERAL WALL PORTION, SAID BLADE PORTION INCLUDING A COLLAR LOCATED PROXIMATE THE BASE THEREOF, SAID COLLAR HAVING A FIRST SURFACE ADAPTED TO ENGAGE SAID EXTERNAL PERIPHERAL WALL PORTION OF SAID HUB, A PLATE MEMBER HAVING A SECOND SURFACE ADAPTED TO ENGAGE SAID INTERNAL PERIPHERAL WALL PORTION OF SAID HUB, SAID BLADE PORTION AND SAID PLATE HAVING A CLEARANCE THEREBETWEEN IN THEIR MOUNTED POSITION, APERTURE MEANS IN SAID HUB, TIE MEANS ON OPPOSITE SIDES OF SAID BLADE PORTION EXTENDING THROUGH SAID APERTURE MEANS AND BETWEEN SAID COLLAR AND SAID PLATE MEMBER FOR DRAWING SAID COLLAR AND SAID PLATE MEMBER TOWARD EACH OTHER UNTIL SAID COLLAR AND SAID PLATE MEMBER MOUNT SAID BLADE CONSTRUCTION AGAINST MOVEMENT ON SAID HUB BY SANDWICHING A PORTION OF SAID HUB IN FIRM CLAMPED ENGAGEMENT BETWEEN SAID FIRST AND SECOND SURFACES, MEANS FORMING A PART OF SAID TIE MEANS AND LOCATED PROXIMATE AND PERIPHERAL EXTERNAL SURFACE FOR EFFECTING LOOSENING AND TIGHTENING OF SAID TIE MEANS FROM A POSITION EXTERNAL TO SAID HUB, SAID LOOSENING OF SAID TIE MEANS PERMITTING ADJUSTMENT OF SAID BLADE CONSTRUCTION ON SAID HUB BY INCREASING THE CLEARANCE BETWEEN SAID PLATE MEMBER AND SAID COLLAR AND THEREBY PERMITTING MOVEMENT OF SAID BLADE CONSTRUCTION ON SAID HUB, AND MEANS ASSOCIATED WITH SAID TIE MEANS FOR LOCKING SAID TIE MEANS AGAINST UNDERSIRED LOOSENING AFTER SAID TIE MEANS HAVE BEEN TIGHTENED. 